• Cultivation of American Wild Yam

    By Richo Cech

    American wild yam (Dioscorea villosa or D. quaternata) is native to the Central and Eastern United States, from Minnesota south to Texas and across to the Atlantic States, excluding the states of northern New England. In northern areas, it can be grown very successfully in a greenhouse, as the plants prefer filtered light and warm, moist conditions. In southern states or on the western seaboard and California, wild yam may be readily propagated outdoors. It prefers a site in open woodlands or at the edge of the forest, where there is partial sun exposure, and where there are small trees and brush for the vines to climb.

    Propagation is either by seed (difficult) or by root cutting (easy). Seeds develop only on female plants, as wild yam is dioecious. In the characteristic three-winged seedpod, each section contains two discshaped, winged seeds. These seeds may be removed from the mature, dry pod and sown immediately, or may be stored for planting at a later time. They should be sown in the fall, midwinter or very early spring, outdoors in pots, flats or directly in a shaded woodland nursery bed. Germination occurs in the spring as the ground warms up. The cold conditioning period, natural rain, snowfall and oscillating temperatures afforded by sowing the seeds outdoors is a good stimulus to efficient germination. The seedlings are quite sensitive and should be left undisturbed for two years, except (of course) to keep them weeded and watered. Then, once the rootlet begins to swell into a rhizome, the seedling may be transplanted to its final location. Raising wild yam from seed takes four years from sowing to harvest of a good-sized root.

    Root cuttings are generally made in the fall, after the parent plant has matured its fruit and started to die back. Choose the young, vigorous and growing portions of the rhizome, which are covered with many root hairs, then cut or break the piece to at least two inches in length. The cuttings are best planted out immediately, thereby allowing them to become accustomed to the new environment before the growing season. Plant the running rhizome about 2 inches deep, with the root hairs down. Spring transplanting is possible, but disturbance at this time of year can damage the newly emerging vines. Planted in a good spot in the woods, a nice cutting will grow into a harvestable sized plant in two or three years. Planted in shaded beds or pots in the greenhouse, the plants will attain harvestable size in a single season, with significant added yield if the plants are allowed to grow for a full two years.

    I enjoy growing wild yam in the west. It has a magical way about it, humming a little plant tune to itself as it courses about, looking for a twiggy hold and a place to hang its seedpods away from the moist forest soil. The vines are delicate and attractive, the seedpods are really interesting, and the roots yield plenty of medicine with very little upkeep.

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